Fins of the type used for attachment to heat exchanger tubes, such as those used in heating, air-conditioning and heat exchange equipment, are conventionally formed on a ribbon-type fin line apparatus. This apparatus acts on a sheet of suitable material such as sheet metal to simultaneously form a plurality of plate-like fins during each cycle of operation. In addition to severing the finished fins from the sheet stock, the apparatus also simultaneously forms several holes through each fin so that they can be positioned in surrounding relationship to appropriate heat exchanger tubes.
While this known fin line apparatus is able to produce fins at a relatively high rate, there was thought to be a maximum rate of fins that could be produced by the fin line apparatus because of constraints in handling the sheet metal stock as it enters and exits the punch press. Problems at the exit are particularly acute when the sheet metal is very thin, such as 0.002 to 0.008 inches. Further, as the sheet metal stock is gripped and moved from one position to another as the sheet metal stock passes through the punch press, faster and faster cycling times pose serious problems in assuring that the sheet metal stock is appropriately gripped and moved from position to position as the punch press systemically forms several holes through each fin. One "misfeed" of the sheet metal stock causes the work product so produced to be flawed and unusable. The maximum rate under carefully controlled constraints was about 300 cycles per minute. In an uncontrolled environment, such as out in the field, the maximum rate was about 250 cycles per minute.
Accordingly, it is an object of this invention to provide a sheet metal control apparatus which assures a consistent intermittent feeding of the sheet metal stock through the punch press at cycle times not heretofore thought possible, namely, at cycle times in excess of 300 cycles per minute, particularly in the range of 400 to 700 cycles per minute and even faster.
It is a further object of the invention to provide a sheet metal control apparatus which is capable of a high frequency intermittent driving movement of the sheet metal stock through the punch press where the sheet metal stock necessarily must be held perfectly stationary while the punch press does its work and then be flawlessly accelerated quickly so as to cause the sheet metal to move from station to station through the punch press.
It is a further object of the invention to provide a sheet metal control apparatus, as aforesaid, wherein sheet metal stock supplied to the punch press from a roll form thereof passes through a trough whereupon air blowing means solely urges the sheet metal stock to a taut condition so as to prevent violent fluttering of the sheet metal stock caused by the high frequency moving and stopping of the sheet metal stock as it is drawn into the punch press from the roll.
It is a further object of this invention to provide a sheet metal control apparatus, as aforesaid, wherein an air blowing means blows the sheet metal stock into a supporting wall surface to further keep the sheet metal stock from wrinkling and otherwise becoming deformed prior to entry into the punch press.
It is a further object of the invention to provide a sheet metal control apparatus wherein a discharge or removal device is provided adjacent the outlet from the punch press to facilitate in the rapid removal of the finished sheet metal fin stock formed by the punch press.
It is a further object of the invention to provide a sheet metal control apparatus, as aforesaid, wherein the discharge or removal device includes a strip of wire extending transversely of the longitudinal axis of the sheet metal fin stock, which strip of wire drives the finished sheet metal fin stock away from the outlet of the punch press simultaneously with the severing of the sheet metal fin stock to its finished lengths.
It is a further object of the invention to provide a sheet metal control apparatus which is reliable in operation and requires minimal maintenance.